Just this morning I did the biggest bonehead mistake I've ever made in any game.
Founded Moscow, and scouted a location for a second city, on a coast/plains hill covered by jungle, 2 tiles away from MARBLE. Since MARBLE is one of the rarest resources (at least in my experience) I decided to build there ASAP so I could grab The Oracle, Parthenon & Great Library, wonders which I always miss due to lack of Marble.
Once my settler got in position, the game recommended an alternate location, one tile NW on a forested hill (but still on the coast.) I studied the map and decided it was in fact a better location, the marble will just take 2 border expansions instead of one to get the marble online. And since I'm Catherine (creative) that shouldn't take very long.
However, I didn't want to waste that forest. So I delayed placing the settler for about 4 turns so my worker could chop it. This set up a number of delays and missteps that cascaded through the next several turns -- Stonehenge was FIDAL (before I could even start building it) and so was The Oracle, 3 turns away and in the middle of a forest chop.

Plus, St. Petersburg was having health problems since I'd removed that one forest and had a lot more jungle to deal with (and didn't have IW due to losing the Oracle race...)
Still, everything was going smoothly right up until it was time for the next border expansion. I'd built a road to the marble, had two workers waiting there to get the quarry going, the borders popped and...
...I didn't get it. Got the tile right above and to the west of the marble, but not the marble itself. Totally forgot about the way borders grow!
Had to back up 1500 years to fix that massive blunder!!
